A Defense Department policy memo quietly released last month has left Marine Corps infantry units unable to use the hundreds of new quadcopters fielded to units at the direction of the commandant.

The policy, which bars the purchase or use of any commercially available unmanned aerial systems (UAS), also means that off-the-shelf small drones used by public affairs troops are sitting idle.

And 3D-printed quadcopters like "The Nibbler," produced by Marines downrange, are not exempt either. While their bodies are printed on demand, their inner workings are not and may represent a security risk, according to the new memo.

Released May 23 and signed by Under Secretary of Defense Patrick Shanahan, the memo cites a May 14 Defense Department Inspector General report that found the Pentagon did not have adequate procedures to assess cybersecurity risks associated with using commercial drone systems.

Many of the most popular commercial UAS are Chinese-made, prompting concerns that they could come with embedded malware enabling the user to be surveilled or otherwise hacked.

The potential for a security breach has long been a concern for the military. In August, the Army Aviation Directorate banned the use of drones made by the most popular commercial company, DJI, which is Chinese-owned.

But the indefinite and broad-edged nature of the new DoD policy memo is likely to leave many units that have leaned into drone acquisition at the direction of their leaders sitting on their hands and without clear recourse. The ban is in place, according to the memo, "until the DoD develops a strategy to adequately assess and mitigate the risks associated with their use."

Any requests for exemptions must be approved by Shanahan himself on a case-by-case basis, and must support "urgent needs," according to the memo.

The Marine Corps, he said, is in the process of requesting an exemption to allow troops to use these systems. It's not clear, however, what "urgent needs" rationale would support the request or how long it might take to obtain a waiver.

Pena said other units that own commercial UASs include science and technology elements, ground combat elements, logistics units, and public affairs.

"Right now, the priority is to request exemptions for [ground combat element] assets, to include 'Quads for Squads,' " he said.